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Grafting susceptible crop plants on disease and pest-resistant rootstocks is a valuable management practice for reducing damage caused by plant-parasitic nematodes and plant pathogens in vegetable and fruit tree crops worldwide. By combining pedigree-based genetic information with quantitative phenotypic data, it would be easier to identify and select rootstocks with superior trait combinations needed for rootstock development using marker-assisted-selection, enabling rapid selection of successive-generation rootstocks with the desirable trait combinations for development of marketable rootstocks. [...]when a susceptible scion is grafted on a rootstock with low susceptibility, the rootstock susceptibility may be increased. [...]it is important to evaluate each scion/rootstock combination and not rely on rootstock performance alone since there may be unexpected scion/rootstock interactions. Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Background Cultivation of resistant rootstocks can effectively prevent apple replant disease (ARD), and grafting tests are an important means of evaluating the compatibility of rootstocks with scions. Methods The apple rootstocks 12–2 (self-named) and Malus hupehensis Rehd. (PYTC) were planted in a replanted 20-year-old apple orchard. The two rootstocks were grafted with scions of 13 apple varieties. Multiple aboveground physiological parameters of the grafted combinations were measured and evaluated to verify the grafting affinity of 12–2 with the scions as compared to Malus hupehensis Rehd. (PYTC). Results The graft survival rate and graft interface healing of 12–2 did not differ significantly from those of PYTC. Mechanical strength tests of the grafted interfaces showed that some mechanical strength indices of Redchief, Jonagold, Starking, Goldspur and Yinv apple varieties were significantly higher when they were grafted onto 12–2 compared to the PYTC control. The height and diameter of shoots and the relative chlorophyll content, photosynthetic and fluorescence parameters, antioxidant enzyme activities and malondialdehyde content of leaves showed that Fuji 2001, Tengmu No.1, RedChief, Gala, USA8, and Shoufu1 grew similarly on the two rootstocks, but Tianhong 2, Lvguang, Jonagold, Starking, Goldspur, Yinv and Luli grew better when grafted onto 12–2 than onto the PYTC control. The rootstock 12-2, therefore, showed good grafting affinity. Conclusion These results provide experimental materials and theoretical guidance for the cultivation of a new grafting compatible rootstock to the 13 studied apple cultivars.

The cultivation of resistant rootstocks is one of the more effective ways to mitigate apple replant disease (ARD). We performed an ion current test, a pot experiment, and a pathogen infection test on the apple rootstocks 12-2 (self-named), T337, and M26. The ion current test showed that exposure to ARD soil extract for 30 min had a significant effect on K + ion currents at the meristem, elongation, and mature zones of the M26 rhizoplane and on Ca 2+ currents in the meristem and elongation zones. ARD also had a significant effect on Ca 2+ currents in the meristem, elongation, and mature zones of the T337 rhizoplane. Exposure to ARD soil extract for 5 min had a significant effect on K + currents in the meristem, elongation, and mature zones of 12-2 and on the Ca 2+ currents in the elongation and mature zones. Compared to a 5-min exposure, a 30-min exposure to ARD extract had a less pronounced effect on K + and Ca 2+ currents in the 12-2 rhizoplane. The pot experiment showed that ARD soil had no significant effect on any root architectural or physiological parameters of 12-2. By contrast, ARD soil significantly reduced some root growth indices and the dry and fresh weights of T337 and M26 compared with controls on sterilized soil. ARD also had a significant effect on root metabolic activity, root antioxidant enzyme activity (except superoxide dismutase for T337), and malondialdehyde content of T337 and M26. Pathogen infection tests showed that Fusarium proliferatum MR5 significantly affected the root structure and reduced the root metabolic activity of T337 and M26. It also reduced their root antioxidant enzyme activities (except catalase for T337) and significantly increased the root malondialdehyde content, reactive oxygen levels, and proline and soluble sugar contents. By contrast, MR5 had no such effects on 12-2. Based on these results, 12-2 has the potential to serve as an important ARD-resistant rootstock.

Fusarium wilt in bitter gourd caused by Fusarium oxysporum f. sp. momordicae (Fomo) is a severe plant disease that affects the world’s bitter gourd (Momordica charantia L.) cultivation. This study evaluated nine luffa hybrids for their performance as rootstocks with bitter gourd to control Fusarium oxysporum f. sp. luffae (Folu) isolate Fomh16 and Fomo isolate Fomo33. In the first evaluation, five hybrids (LF1, LF2, LF3, LF15, and LF16) exhibited resistance to the Fomh16 isolate and showed no symptoms. One hybrid, LF10, was resistant with a mean disease rating (MDR) of 0.9 at 28 days post-inoculation (dpi). Seven luff hybrids that displayed resistant and moderate resistance in the first evaluation were used as rootstocks with susceptible bitter gourd cultivars. Five rootstocks exhibited high resistance to Fomh16 and Fomo33 isolates, with their MDR ranging from 0.0 to 0.7. In addition, the findings revealed that both isolates could colonize the vascular bundle of all resistant luffa rootstocks at 28 dpi. However, the Fomo33 isolate could extend and colonize the vascular bundle of bitter gourd scion when grafted only with rootstock LF5 and LF11. The quantitative PCR results indicated that there were significant differences in the amount of the Fomo33 DNA between the bitter gourd grafted onto LF15 and LF16 rootstocks and the self-grafted plants; however, the pathogen cannot be detected in the bitter gourd scions grafted with resistant rootstocks. These findings provide valuable resistant sources that can be used as rootstocks to manage Fusarium wilt disease in bitter gourd.

(1) Background: Cultivating resistant rootstocks is an effective way to mitigate apple replant disease (ARD), and we developed superior apple rootstock line 12-2 (self-named), which shows improved ARD resistance. (2) Methods: We used ARD-associated pathogen Fusarium proliferatum MR5 (MR5) to test the fungal infection in the 12-2 line. Seedlings of the 12-2, T337, and M26 rootstock lines were planted in a substrate with potato dextrose broth and MR5 spore solution, and aboveground physiological indicators were measured. (3) Results: MR5 had the greatest effect on the leaf growth of T337 and M26. The incidence rates of infectious symptoms in the T337 and M26 lines were 68 and 100%, respectively. MR5 significantly affected the leaf chlorophyll content, ETR, and NPQ of T337 and M26, as well as Pn and Tr of M26. MR5 tended to reduce the leaf photosynthetic parameters of T337, but the decreases were not significant. The leaf reactive-oxygen-species levels of T337 and M26, the leaf antioxidant-enzyme activities of M26, and the superoxide-dismutase activity of T337 were significantly affected by MR5. MR5 also had a significant effect on the leaf malondialdehyde, proline, and soluble-sugar contents of T337 and M26. None of these aboveground physiological indicators were affected by MR5 in the 12-2 rootstock. (4) Conclusions: The 12-2 rootstock was more resistant to ARD-associated MR5 and could serve as an important test material for resistant-apple-rootstock breeding in China.

(1) Background: The cultivation of resistant rootstocks is an effective way to prevent ARD. (2) Methods: 12-2 (self-named), T337, and M26 were planted in replanted and sterilized soil. The aboveground physiological indices were determined. (3) Results: The plant heights and the stem thicknesses of T337 and M26 were significantly affected by ARD. Relative chlorophyll content (June–October), Pn (August–September), and Gs (August) of T337 and relative chlorophyll content (June–July, September), Pn (September–October), and Ci (September) of M26 were significantly affected by ARD. ARD had a significant effect on Fv/Fm (June), qP (June–July), and NPQ of T337 (June–October, except August) and Fv/Fm (June) and NPQ (June-October, except July) of M26. Additionally, ARD affected Rfd of M26 and T337 during August. SOD (August and October), POD (August–September), and CAT (July-August, October) activities and MDA (September–October) content of T338 as well as SOD (July–October), POD (June–October), and CAT (July-October) activities and MDA (July, September–October) content of M26 were significantly affected by ARD. ARD significantly reduced nitrogen (October), phosphorus (September–October), and zinc (July) contents of M26 and potassium (June) content of T337. The above physiological indices were not affected by ARD in 12-2. (4) Conclusions: 12-2 could be useful as an important rootstock to relieve ARD due to strong resistance.

The density of herbaceous crops creates a suitable environment to produce pathogens in the soil that intensify the attack of pathogens traditionally controlled by disinfectant, which are mostly prohibited and unlisted because of their toxicity. Grafting is an alternative technique to enhance abiotic stress tolerance and reduce root diseases due to soil-borne pathogens, thus enhancing crop production. This research study was conducted during the crop season of 2017 and 2018 in order to investigate the interactive effect of different grafting techniques of hybrid scion onto local rootstocks on plants survival, plant phenological growth, fruit yield and fruit quality under a controlled environment. The hybrid cucumber was also planted self-rooted. The cucumber (Cucumis sativus L.) cv. Kalaam F1, Syngenta was grafted onto four local cucurbitaceous rootstocks; ridge gourd (Luffa operculate Cogn.), bitter gourd (Momordica charantia L.), pumpkin (Cucurbita pepo L.), bottle gourd (Lagenaria siceraria (Molina) Standl.) using splice grafting, tongue approach, single cotyledon and hole insertion grafting techniques and self-rooted hybrid cucumber under greenhouse conditions. The experimental results indicated that all local cucurbitaceous rootstocks showed a high compatibility with hybrid cucumber scion in the splice grafting method compared to other grafting and non-grafted methods. Lagenaria siceraria rootstocks were found highly compatible with cucumber cv Kalaam scion which gave significantly maximum plant survival rates (95%) due to high sap contents, high SPAD value, better vegetative growth and maximum fruit yield when compared with other rootstocks by employing the splice grafting method followed by tongue approach, single cotyledon and hole insertion grafting while the fruit quality of all rootstocks was observed to be similar. The non-grafted cucumber cv. Kalaam F1 showed significant results of plant vegetative growth, fruit development and fruit quality and encountered grafting methods while the lowest result were associated with the hole insertion grafting method in all scion/rootstock combinations. The grafted plants have no significant effect on cucumber fruit dry matter and fruit quality while the fruit mineral compositions (N, P, K, Ca and Mg) were higher among grafted and non-grafted plant fruits. The results indicate that grafting hybrid cucumber onto four local cucurbitaceous rootstocks influenced growth, yield and fruit quality. Grafting can be alternative and control measure for soil-borne disease and to enhance cucumber production.

This study was conducted to investigate the resistance of 4 wild eggplant species (Solanum aethiopium group Aculeatum, S. incanum, S. macrocarpon, S. linnaeanum), 3 cultivated eggplant varieties (‘Anamur F1’, ‘Pala’, ‘Yamula’), 1 eggplant rootstock (Köksal F1) and 34 interspecific hybrids to Verticillium dahliae Kleb. and Fusarium oxysporum f.sp. melongenae. Disease resistance of eggplant genotypes was determined by the pathogenicity test. The disease severity values varied between 0–80% for Verticillium and between 0–100% for Fusarium. Among the 42 genotypes, 18 genotypes were found to be moderately resistant and 1 genotype was found to be highly resistant to Verticillium. At the same time, 2 of the 42 genotypes were found to be moderately resistant and 22 of the 42 genotypes were found to be highly resistant to Fusarium. All hybrids with S. integrifollium, Solanum aethiopicum group Gilo as father were found to be highly resistant to Fusarium oxysporum f.sp.melongenae. Solanum linnaeanum did not exhibit any disease symptoms and was found to be highly resistant to both disease agents. Present interspecific hybrid eggplant genotypes with known resistance to Verticillium and Fusarium wilt are expected to have significant contributions in developing new eggplant rootstocks and hybrid eggplant cultivars in the future.

The global avocado industry is growing, and farmers are seeking to expand their plantations. However, many lands suitable for avocado planting were previously cultivated with hosts of the soil-borne fungal pathogen Verticillium dahliae, which is the causal agent of Verticillium wilt (VW). VW can seriously impair avocado orchards, and therefore, planting on infested soil is not recommended. The use of different rootstock types allows avocado cultivation in various regions with diverse biotic and abiotic constraints. Hence, we tested whether genetic variance among rootstocks may also be used to manage avocado VW. Six hundred trees, mostly Hass and some Ettinger, grafted on 23 selected rootstocks were evaluated for five years in a highly V. dahliae-inoculated plot for VW symptoms, fungal infection, and productivity. The selected rootstocks displayed a significant variation related to VW tolerance, and productive avocado rootstocks with potential VW tolerance were identified. Moreover, the rootstock productivity appears to correlate negatively to the susceptibility level. In conclusion, planting susceptible rootstocks (e.g., VC66, VC152, and VC26) in infested soil increases the likelihood of massive tree loss and low productivity. Whereas, tolerant rootstocks (e.g., VC804 and Dusa) may restrict VW and enable avocado cultivation on infested soils.

Citriculture is considered the most important fruit industry and involves the cultivation of several fruit varieties, which are susceptible to many plant pathogens. In this sense, soil-borne pathogenic fungi, such Rosellinia necatrix, threaten citrus fruit production worldwide because they can cause fruit loss. Therefore, we assayed the physiological reaction of novel citrus rootstocks against white root rot disease during long-term management. Data from above-ground symptoms and chlorophyll content were periodically obtained during the experimental process. In addition, plant leaf area and percentage of biomass reduction were determined for each rootstock when the experiment finished. The behavior of the inoculated tolerant rootstocks was as follows: the lowest symptom rate of SAUDPC was achieved by B11R5T25 and N40R3T25; AMB+CZO manifested the highest disease incidence; B11R5T25 and A+VOLK × Orange 19-11-8 displayed the highest and the lowest chlorophyll content, respectively; AMB+CZO and A+VOLK × Orange 19-11-8 showed the highest biomass reduction, and the lowest was detected in B11R5T25 and N40R2T19; concerning the leaf area, N40R1T18, N40R3T25 and N40R2T19 showed the lowest response, and 2247 × 2075-01-2 achieved the highest rate. In summary, B11R5T25 and N40R3T25 displayed the lowest disease rate.